Traditional cough tinctures do not exclude onion, lemon, and olive oil, but there is no convincing proof that the particular mixture will entirely wipe out a cough the next day. Some constituents (onion, lemon, and oils or honey) may ease the discomfort of mild coughs, but they do not become a sure thing or an acknowledged cure, particularly in case of severe infections.
What is known about these ingredients Onion: Conventional cough syrup and poultices made from onion are very much in use when a person suffers from cough and chest congestion, and the reason behind this is probably the consumption of onion being the source of an expectorant, anti-inflammatory, and antimicrobial agent. Onion and honey combined then has very much to do with the relieving of colds and coughs at home.
Lemon: It is common for lemon juice to be mixed with honey and, occasionally, onion in “grandma’s syrups” for the purpose of thinning the mucus and soothing the throat, and the lemon also supplies vitamin C and a degree of acidity that may be perceived as soothing. Olive oil: In some homemade remedies for cough, a mixture of olive oil, honey, and lemon is used to provide a coating and lubrication to the throat that is dry and irritated, thus lessening the pain caused by coughing. Example home mixture (symptom relief) A recipe that is well known and shared by many combines the following: 1–2 tablespoons of honey (if not allergic, and never for children under 1 year), juice from about half a lemon, 1-2 teaspoons of a mild oil like extra-virgin olive oil blended into a smooth syrup that can be taken by the spoon several times a day to relieve the throat. Onion-based remedies of old usually suggest combining onion not only with honey or sugar (or as a warm poultice) but also with olive oil and lemon. Evidence and safety points There are clinical studies that report honey can diminish the number of coughs and their severity in upper respiratory infections concurrent with usual treatment, especially in kids over one year, but it does not imply the cough disappears overnight. The efficacy and safety of onion-lemon-olive-oil mixtures are not supported by any clinical trial of high quality.